Drop go-getter use.

[monopole]

Fix #3578

Only the first commit (d564df5) has manual changes, the rest is due to go tidy etc. Lots of deps are dropped.

The build command's help had to be changed since it mentioned gogettter; took the opportunity to make the cobra command object more reusable, so we have the option of using it directly in kubectl.

ALLOW_MODULE_SPAN

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[natasha41575]

so kustomize is no longer supporting building from remote repos? just checking that I understand the purpose of this PR

[monopole]

It still supports URLs like

kustomize build https://github.com/kubernetes-sigs/kustomize.git/examples/helloWorld?ref=v1.0.6

[Shell32-Natsu]

so kustomize is no longer supporting building from remote repos? just checking that I understand the purpose of this PR

go-getter is the first method kustomize tries to get the remote resources. After removing it the secondary method (git cloner) will be the primary one. It may break some users' remote resources and probably reduce performance but we have to do it since license issue and massive dependencies.

[Shell32-Natsu]

/lgtm

[monopole]

Under the hood, it uses git clone in a subprocess.

The argument to build, or any entry in the resources, generators, transormers, components or validators, is parsed into a RepoSpec to separate the url part from the directory part.

The URL is passed to a subprocess that runs git clone to pull into a temp dir. Then the YAML is pulled from the appropriate subdir of that temp dir. So kustomize still honor's whatever git clone honors.